Add a "max_size" parameter to diff_delta()

diff --git a/pack-objects.c b/pack-objects.c
index dfa9d44a15625d71a93418c2c5bd996441c79506..d9328a98d8f349b75fc5ab8302b66116317781ec 100644 (file)
--- a/pack-objects.c
+++ b/pack-objects.c
@@ -83,8 +83,8 @@ static void *delta_against(void *buf, unsigned long size, struct object_entry *e
 
        if (!otherbuf)
                die("unable to read %s", sha1_to_hex(entry->delta->sha1));
-        delta_buf = diff_delta(buf, size, otherbuf, othersize, &delta_size);
-        if (delta_size != entry->delta_size)
+        delta_buf = diff_delta(buf, size, otherbuf, othersize, &delta_size, ~0UL);
+        if (!delta_buf || delta_size != entry->delta_size)
                die("delta size changed");
         free(buf);
         free(otherbuf);
@@ -292,6 +292,7 @@ static int try_delta(struct unpacked *cur, struct unpacked *old)
        struct object_entry *cur_entry = cur->entry;
        struct object_entry *old_entry = old->entry;
        unsigned long size, oldsize, delta_size;
+       long max_size;
        void *delta_buf;
 
        /* Don't bother doing diffs between different types */
@@ -300,6 +301,8 @@ static int try_delta(struct unpacked *cur, struct unpacked *old)
 
        /* Size is guaranteed to be larger than or equal to oldsize */
        size = cur_entry->size;
+       if (size < 50)
+               return -1;
        oldsize = old_entry->size;
        if (size - oldsize > oldsize / 4)
                return -1;
@@ -311,15 +314,14 @@ static int try_delta(struct unpacked *cur, struct unpacked *old)
         * more space-efficient (deletes don't have to say _what_ they
         * delete).
         */
-       delta_buf = diff_delta(cur->data, size, old->data, oldsize, &delta_size);
+       max_size = size / 2 - 20;
+       if (cur_entry->delta)
+               max_size = cur_entry->delta_size-1;
+       delta_buf = diff_delta(cur->data, size, old->data, oldsize, &delta_size, max_size);
        if (!delta_buf)
-               die("unable to create delta");
-       if (delta_size + 20 < size / 2) {
-               if (!cur_entry->delta || cur_entry->delta_size > delta_size) {
-                       cur_entry->delta = old_entry;
-                       cur_entry->delta_size = delta_size;
-               }
-       }
+               return 0;
+       cur_entry->delta = old_entry;
+       cur_entry->delta_size = delta_size;
        free(delta_buf);
        return 0;
 }